December, 1958 



Decker: Economic Entomology 



111 



vigorously growing orchard trees — an ex- 

 cellent example of how man creates, or at 

 least aggravates, his own insect problems. 

 The more man prunes and fertilizes, the 

 more certain he is to develop a serious San 

 Jose scale problem. 



Truck Crop Pests 



An article, probably by Walsh, pub- 

 lished in 1869 makes it clear that at an 

 early date a host of insects were recog- 

 nized as important pests of a wide vari- 

 ety of vegetable crops: 



There is scarcely a vegetable raised in our 

 gardens that is not preyed upon by one or 

 more grubs, caterpillars, or maggots, so that, 

 when we eat it, we have positively no security 

 that we are not mingling animal with vegeta- 

 ble food. Two distinct kinds of maggots, pro- 

 ducing two distinct species of two-winged Fly. 

 burrow in the bulb of the onion. Scabby po- 

 tatoes are inhabited by a more elongated 

 maggot, producing a very different kind of 

 two-winged Fly, and also by several minute 

 species of Mites. Turnips, beets, carrots and 

 parsnips are each attacked by peculiar larvae. 

 And as to the multifarious varieties of the 

 cabbage, not only are they often grievously 

 infested by the Cabbage Plant-louse — a species 

 which has been introduced from Europe into 

 this country — but also by an imported cater- 

 pillar producing a small moth, and by several 

 indigenous caterpillars producing much larger 

 moths, some of which caterpillars, when full- 

 grown, are over one inch long (Walsh & Rilev 

 1869:114). 



Why the article failed to include the 

 corn earworm, the squash vine borer, the 

 cucumber beetles, and the melon louse is 

 hard to say, for they were numbered 

 among the best known pests at the time. 

 One is amazed that the Colorado potato 

 beetle was not mentioned, because this 

 species was the most spectacular insect 

 pest of vegetable crops in Illinois in the 

 latter half of the 1860's. Presumably, 

 prior to 1850 the Colorado potato beetle 

 was unknown except as an interesting 

 species found only in the foothills of the 

 Rocky Mountains, where it fed on a wild 

 potato somewhat resembling the common 

 horse nettle. When the pioneers planted 

 Irish potato and egg plant in Nebraska 

 and Colorado, the beetle found these 

 closely related plants to its liking, in- 

 creased its numbers many fold, and took 

 ofi for the East, flying from one settler's 

 potato patch to another's. Here again we 

 have an example of how man may create 



his own insect control problems. The in- 

 troduction of a crop highly attractive to a 

 native insect invites this insect to trans- 

 fer its affections to the newly introduced 

 crop. The potato beetle transferred its 

 afifections from its native host to the in- 

 troduced potato. It seems quite probable 

 that the potato beetle's many natural en- 

 emies did not travel eastward but con- 

 tinued searching for it in its old haunts. 

 With an abundance of lush, nutritious 

 potato vines and a temporary release from 

 its natural control agencies, the Colorado 

 potato beetle, in the vernacular of today, 

 "went to town" until a new system of 

 checks and balances could be established. 

 The eastward movement of the potato 

 beetle was first noted in eastern Colorado 

 in 1859. It did not appear in Illinois un- 

 til 1864. Damaging populations of this 

 beetle were reported in several Illinois 

 counties in 1865. Some of the tales of 

 wholesale potato destruction related in 

 the local press and the Prairie Farmer 

 were downright pathetic: 



"Let every man and woman in the country or 

 in town, who has a potato patch, try experi- 

 ments for the destruction of these pests and 

 report progress. Something must be done to 

 stop the destruction of the vines by these in- 

 satiate creatures or we may as well quit trying 

 to raise potatoes" (Cedar Valley, loiva, Times, 

 quoted by Riley 1866:432). 

 I know of several cases near Rock Island, Illi- 

 nois, where the owners of potato-patches, after 

 persevering in a course of hand-picking for 

 fully a month, finally gave up in despair, be- 

 cause as fast as they killed off their own bugs, 

 a fresh supply from their neighbors' potato- 

 patches kept flving in upon them (Walsh 

 1866:14). 



All accounts seem to agree that neither lime, 

 nor ashes, nor any available external applica- 

 tion is of the least use in checking the depre- 

 dations of this insect. The Prairie Farmer says 

 that "Mr. Jones found, after many experi- 

 ments, that neither hot lime, lime-water, brine, 

 tobacco-water, wine (?) nor sulphur had any 

 effect on them ; that turpentine, benzine and 

 kerosene would kill them when copiously ap- 

 plied, but also killed the potatoes" and that 

 "coal-oil mixed with water is ineffectual." 

 . . . Although there is some contradictory evi- 

 dence, yet the general result of all the testi- 

 mony is, that neither domestic fowls, nor ducks, 

 nor turkeys will eat them, at all events to any 

 very extensive amount (Walsh 1866:14). 



Hand picking, or the manual collection 

 and destruction of the beetles, their lar- 

 vae, and their eggs, was about the only 

 really effective control measure. During 



